单缸柴油机进气系统对充量系数的影响

充量系数直接影响发动机的动力性及经济性,作者试验研究了进气系统各参数对充量系数的影响,并把在静态下得到的结论推广应用到动态状况。并编制了带空滤器边界模型的电算程序,用这个为试验所证实了的方法对充量系数进行了预测,有效地代替了常规试验。     

高能效系数家用太阳能热水系统的实现

通过总结高能效系数家用太阳能热水系统研发和实现过程中的经验及做法,指出高能效系数产品的实现涉及研发、设计、工艺、生产、检测等各环节,产品实现过程中每一个环节均发挥着非常重要的作用,缺一不可。     

基于奇异摄动模型的风能转换系统H∞容错保性能控制

在风能转换过程中,针对执行器故障、容错控制成本高等问题,设计了H_∞最优容错保性能控制器,并基于PI观测器进行了故障诊断。首先,将风电系统中存在的时滞、参数不确定、执行器故障等问题用奇异摄动LPV模型表达;然后,设计PI观测器进行执行器故障重构,并在H_∞性能指标和成本性能指标双重约束下,进行凸优化计算,得到最优容错保性能控制律。仿真表明,低风速时,控制器能有效跟踪最优风轮转速,实现最大风能捕获。     

多连接式双水箱太阳能热水系统的应用探讨

为解决双水箱太阳能热水系统存在的辅助能耗大、集热面积与水箱不匹配等问题,从传统的双水箱系统出发,分析了双水箱系统连接方式存在的阻力问题;提出了双水箱太阳能热水系统多连接方式的设计思路;用试验测试方法分析了系统设计效果。研究内容为太阳能双水箱系统的工程应用提供了参考。     

基于热电制冷的车用太阳能空调系统CSCD

本工作研究了基于热电制冷的车用太阳能空调系统,该系统通过太阳能板独立供电并对模拟车厢空间温度进行调节。试验系统包括太阳能板、锂电池等供能装置及由热电制冷片所组成的空调制冷系统,电池模组采用1×4方形磷酸铁锂电池串联组成,模拟箱体尺寸为400 mm×400 mm×400 mm,内置6个温度传感器进行气温测量,侧壁安置热电偶和热流计以测量壁面温度和通过壁面的热流量。试验研究了太阳能空调的制冷性能,获得了在热电制冷片串联和并联连接情形下箱体的降温曲线,实时测量试验箱体内的热流量,分析了热电制冷片的制冷工作效率及其计算方法。结果表明,环境温度为27℃,两块热电制冷片串联情形下持续工作30 min,密闭箱体内平均温度可降至18.3℃,平均制冷系数为1.03,有效制冷系数为0.79(排除壁面热流量);在两块热电制冷片并联时,密闭箱体内平均温度可降至16.7℃,平均制冷系数为0.38,有效制冷系数为0.28 (排除壁面热流量)。     

用喷气式可变涡流进气系统改善柴油机的排放性能

自行研制了一种向螺旋进气道内喷射空气的可变涡流进气系统——喷气式可变涡流进气系统,试验研究了该系统对柴油机排放特性的影响。结果表明,该系统在不影响进气充量系数的情况下,可以明显改变柴油机微粒和氮化物的排放量。其原因在于系统对气缸内涡流强度的改变,直接影响了燃烧与空气的混合、燃烧。对于涡流强度与燃料的燃烧不相匹配的发动机工况,喷气式可变涡流进气系统可以有效改善发动机的排放性能,缓解氮氧化物与微粒排放的矛盾。     

泵与风机系统能量利用性的评价与设计运行优化

泵与风机系统(装置)应用广泛,节能降耗倍受关注.传统分析有明显缺憾,系统设计也难以按照现代设计方法的思想作定量的经济性评估和优化分析.本文阐述了若干新的理论见解和技术思路,可为系统的合理设计、运行及科学的能量利用性评析提供支持,对从事相关工程实践和节能工作指导及评估的人士会有很好的参考价值,也可为专业的水力机械及流体动力工作者提供有益的启示.     

Optimal and stochastic performance of an energy hub-based microgrid consisting of a solar-powered compressed-air energy storage system and cooling storage system by modified grasshopper optimization algorithm

Simultaneous operation of different energy generation and transmission infrastructures is a subject that has been considered under the concept of energy hub. This subject is highly regarded in the field of microgrids. One of the basic issues for investors is to properly utilize the energy hub for optimally managing energy carriers, especially in the energy price prediction. In the present paper, a new strategy is introduced for the energy hub in order to achieve the optimal performance of a microgrid (MG) that includes different energy carriers for each day. The objective of this strategy is to minimize the operation cost and consider the environmental issues. The proposed energy hub consists of a combined cooling-heating-power (CCHP) system along with a wind turbine and photovoltaic cells. The studied energy hub system is composed of an ice storage conditioner (ISC) system and an energy storage system (ESS) as the energy storage resource (ESR). One of the goals of the present work is to investigate the effect of solar-powered compressed-air energy storage (SPCAES) on the performance of the energy hub. The proposed strategy takes into account the uncertainty of the energy resources such as the wind and sun for meeting the electric, thermal, and cooling needs in different scenarios. In the present paper, to produce various scenarios, the Latin hypercube sampling (LHS) method is used. Also, the k-means method is used to reduce the number of scenarios. The objective function is solved using the modified grasshopper optimization algorithm (MGOA). According to the modeling results, the ESS can exhibit successful performance in the energy management strategy.     

Investigation of evacuated tube heated by solar trough concentrating system

Two types of solar evacuated tube have been used to measure their heating efficiency and temperature with fluids of water and N₂ respectively with a parabolic trough concentrator. Experiments demonstrate that both evacuated tubes present a good heat transfer with the fluid of water, the heating efficiency is about 70–80%, and the water is easy to boil when liquid rate is less than 0.0046 kg/s. However, the efficiency of solar concentrating system with evacuated tube for heating N₂ gas is less than 40% when the temperature of N₂ gas reaches 320–460 °C. A model for evacuated tube heated by solar trough concentrating system has been built in order to further analyze the characteristics of fluid which flow evacuated tube. It is found that the model agrees with the experiments to within 5.2% accuracy. The characteristics of fluid via evacuated tube heated by solar concentrated system are analyzed under the varying conditions of solar radiation and trough aperture area. This study supports research work on using a solar trough concentrating system to perform ammonia thermo-chemical energy storage for 24 h power generation. The current research work also has application to solar refrigeration.     

Performance evaluation of high-efficiency SOFC-PEMFC hybrid system fueled by liquid ammonia

The liquid ammonia-fueled SOFC-PEMFC (solid oxide fuel cell-proton exchange membrane fuel cell) hybrid system is studied, and the influence of three factors on the energy efficiency of the system is analyzed. The results show that when the SOFC fuel utilization rate gradually increases, the maximum power of the hybrid system is 1277.85 kW, the total electrical efficiency of the system can reach 62.55%, the combined cooling and power (CCP) efficiency is the highest 69.25%, and the thermoelectric efficiency is gradually increased to 93.19%. When the SOFC operating temperature gradually increases, the electrical efficiency of the hybrid system is the highest 62.72%, the CCP efficiency is 69.41%, and the thermoelectric efficiency is basically maintained at about 90%. When the SOFC operating pressure gradually increases, the total power of the system is up to 1352.19 kW, the electrical efficiency and CCP efficiency of the system are about 60%, and the thermoelectric efficiency of the system is basically maintained between 88% and 95%.     

Assessment of cracks in power plant components by means of the HIDA knowledge-based system (KBS)

An important integrating task in the framework of the HIDA project was the development and application of the knowledge-based system (KBS). The system enables to assess/predict cracks in high-temperature components of power plants operating under creep and/or fatigue conditions, according to the HIDA procedure developed through the other tasks of the project. The system encompasses a comprehensive material database comprising the proprieties of the materials tested within the HIDA project and which are necessary for the analysis. It also includes a library of different component geometries. The system is built in such a way that the data (e.g. material data, component geometry, etc.) necessary for a high temperature crack assessment can be directly entered by the user or selected from the existing databases within the KBS.The HIDA procedure has been integrated in the KBS in a modular sequence, each module enabling to undertake a step of calculation and/or analysis. This structure allows the user to either run the whole procedure or just perform one single step (e.g. check C^* values). In addition, new or alternative procedures can be used, either for the assessment as a whole, or just for single steps (e.g. C^*, 2-criteria diagram, etc.). The system was developed by MPA Stuttgart, as the HIDA KBS task leader, using ALIAS shell (ALIAS — advanced life assessment system) as a basis, and then tested and applied by industrial partners in the HIDA project.The paper describes the functionality and use of the system through reporting selected application cases (CT probe, pipes, pipe bends), and demonstrates the benefits/advantage of such system within the industry.     

Artificial immune system for fixed head hydrothermal power system

This paper presents artificial immune system for optimal scheduling of thermal plants in coordination with fixed head hydro units. Numerical results of two test systems have been presented to demonstrate the performance of the proposed algorithm. The results obtained from the proposed algorithm are compared with those obtained from differential evolution, particle swarm optimization and evolutionary programming technique. From numerical results, it is found that the proposed artificial immune system based approach is able to provide better solution than differential evolution, particle swarm optimization and evolutionary programming in terms of minimum cost and computation time.     

Analyzing a micro-solid oxide fuel cell system by global energy balances

A simple method to predict the thermal characteristics of a micro-SOFC system is presented in this study. The basic design requirements for a thermally self-sustaining operation at a stack temperature of about 550 °C are assessed. Based on steady-state global energy and mass balances, the influence of the electrical efficiency, the overall air-to-fuel ratio and the heat losses on the operating temperature is discussed. It was found that at high electrical efficiencies and, hence, low heat release rates, a recuperator is needed to achieve the desired operating temperature. At lower electrical efficiencies, in contrast, disposing the released heat becomes an issue and an efficient cooling of the stack is required. Whether a recuperator or additional cooling components are necessary also depends on the electrical power output, the stack size and the thermal insulation specifications. The threshold between cooling and recuperator mode is of special interest, since this operating point allows a simple design of the thermal system without recuperator and only a minimum of air to be supplied to the system. This threshold efficiency, which is the maximal electrical efficiency that allows a thermally self-sustaining operation without recuperator, is above 50% under adiabatic operating conditions. In a non-adiabatic system, the threshold efficiency is reduced to about 45% in a 20 W_el and to about 20% in a 2.5 W_el system even with a state-of-the art thermal insulation. The considered thermal insulations dominate the system volume. Therefore, the ability of heat loss minimization is highly dependent on the targeted volumetric power density of the system.     

精益六西格玛方法论证冷水机组节能优化方案

应用精益六西格玛方法,借助Minitab软件,对冷水机组的节能优化方案进行论证。系统收集运行数据,对设备运行负载率、生产供冷负荷进行精确统计,对备选方案的投资回收期进行测算对比,量化论证方案利弊,为企业节能改造项目的优选与实施排序提供数据依据。     

Explaining the rapid diffusion of Dutch cogeneration by innovation system functioning

In this paper, we apply the functions of innovation systems theory to explain the successful diffusion of cogeneration technology in The Netherlands. We show that the technological innovation system for cogeneration functioned very well and that this explains for a major part the successful diffusion. We also show that the innovation system was positively influenced by actions of the Dutch government. Government actions were aligned to the needs of the other parties in the innovation system. Finally, we show that part of the successful diffusion can be attributed to changes in the institutional environment that were not intended to stimulate cogeneration.     

Study of hydrogen production system by using PV solar energy and PEM electrolyser in Algeria

Hydrogen fuel can be produced by using solar electric energy from photovoltaic (PV) modules for the electrolysis of water without emitting carbon dioxide or requiring fossil fuels.     

高压加热器保护系统的配置

高加系统能否安全运行,将直接影响到机组的效率,这就需要有一套齐备安全的保护系统附件.本文简要介绍高压加热器保护系统的配置,以供参考.